1. Field of the Invention
The present invention relates to a multilayer ceramic electronic component such as a multilayer ceramic capacitor, for example, and more particularly to a multilayer ceramic electronic component including an inner electrode including Al as a main component.
2. Description of the Related Art
Firstly, referring to FIG. 1, a multilayer ceramic capacitor 1 as a typical example of a multilayer ceramic electronic component will be described.
Multilayer ceramic capacitor 1 includes a multilayer body 2 constituted by stacked dielectric ceramic layers 3 and a plurality of inner electrodes 4 and 5 formed along certain interfaces between dielectric ceramic layers 3.
In multilayer ceramic capacitor 1 shown in FIG. 1, a first outer electrode 8 and a second outer electrode 9 are formed respectively on opposing end surfaces of multilayer body 2. Inner electrodes 4 and 5 include a plurality of first inner electrodes 4 electrically connected to first outer electrode 8 and a plurality of second inner electrodes 5 electrically connected to second outer electrode 9. These first inner electrodes 4 and second inner electrodes 5 are arranged alternately in the layered direction.
Since miniaturization of a multilayer ceramic capacitor is particularly demanded, a method of layering a green sheet of dielectric ceramic and an inner electrode layer and thereafter firing those concurrently is employed in the manufacturing process. In recent years, a base metal such as Ni is employed in an inner electrode of a multilayer ceramic capacitor for cost reduction.
However, since Ni is very liable to be oxidized when co-sintered with ceramic, it was necessary to precisely control a temperature condition and an oxygen partial pressure under a reductive atmosphere as an atmosphere in the stage of firing. As a result, the material design was greatly limited. Additionally, the problems of delaminations, cracks, and the like due to an uneven stress along with co-firing occurred.
Therefore, inner electrodes of various metal species were considered to try to improve a degree of freedom in designing a multilayer ceramic electronic component.
For example, Japanese Patent Laying-Open No. 2011-97016 describes a multilayer ceramic body employing Al in place of Ni as an inner electrode material, and mechanical characteristics and electrical characteristics are improved by forming an Al2O3 film on a surface portion of the Al inner electrode.
A larger capacitance is desired increasingly for a multilayer ceramic capacitor as a typical multilayer ceramic electronic component. In such a case, the multilayer ceramic electronic component disclosed in Japanese Patent Laying-Open No. 2011-97016 had a problem that an electrostatic capacitance of the multilayer ceramic electronic component becomes scant due to low permittivity of the Al2O3 film present in the interface between the ceramic layer and the Al inner electrode.